For example, according to the technology disclosed in related-art, a document conveying mechanism for implementing a conveyed document reading function and an imaging unit reciprocating mechanism for implementing a placed document reading function are driven by one driving source.
According to the related-art, an imaging unit such as carriage is collided with a cam plate to thus rotate the cam plate. Thereby, transmission of a driving force is switched between a case where the driving force is transmitted to the document conveying mechanism and a case where the driving force is transmitted to the imaging unit reciprocating mechanism.